JP3244255B2 - Semiconductive resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductive resin composition used for a semiconductive layer of a power cable.

[0002]

2. Description of the Related Art An insulated wire core for a crosslinked polyethylene insulated cable is provided for the purpose of alleviating electric field concentration and preventing partial discharge at an interface between an insulating layer and a conductor or an interface between an insulating layer and a metal shielding layer.
A semiconductive layer is provided inside and outside the insulating layer. This semiconductive layer is formed of a semiconductive resin composition obtained by mixing an ethylene-vinyl acetate copolymer, carbon black, and a filler as a base resin.

[0003] However, this resin composition has a disadvantage that it is difficult to peel off. Therefore, when stripping the external semiconductive layer, for example, by connecting a power cable using such a composition for the semiconductive layer, carbon black tends to remain on the insulating layer after stripping. There is a disadvantage that the residual carbon black causes a decrease in insulation resistance and causes tree formation. As a method of solving this drawback, a method of lowering the degree of crosslinking of the ethylene-vinyl acetate copolymer contained therein or increasing the vinyl acetate component in the copolymer can be mentioned. With a decrease in mechanical strength and heat resistance.

As a solution to such a disadvantage, a method of adding dimethylpolysiloxane (silicone oil) has been proposed (JP-A-56-118435). According to this method, the effect of improving the releasability can be obtained without lowering the mechanical strength. However, as a result of various studies, it has been found that a power cable using the resin composition according to the related art for a semiconductive layer has poor tree resistance.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a semiconductive resin composition which does not decrease in heat resistance or mechanical strength and has excellent tree resistance and is easy to peel off. .

[0006]

Means for Solving the Problems The semiconductive resin composition of the present invention contains methylphenyl silicone oil as a component in order to solve the above problems. This methylphenyl silicone oil has a viscosity of 1 mPa / sec or more and 50
It is necessary to be less than 0 mPa / sec. When a semiconductive layer of a power cable is formed using a semiconductive resin composition containing methylphenylsilicone oil having a viscosity of less than 1 mPa / sec, kneading is difficult due to too good slipperiness and peelability. Is improved, but the appearance becomes uneven, which causes a decrease in tracking performance and causes tree generation. On the other hand, a semiconductive resin composition containing a methylphenyl silicone oil having a viscosity of more than 500 mPa / sec is inferior in peelability.

The content of the methylphenylsilicone oil must be not less than 1 part by weight and not more than 10 parts by weight based on 100 parts by weight of the base resin. If the amount is less than 1 part by weight, a good effect of improving the releasability cannot be obtained, and if the amount is more than 10 parts by weight, the slipperiness is too good and the kneading and production becomes difficult.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the semiconductive resin composition of the present invention, a polyolefin resin is used as a base resin in terms of affinity with crosslinked polyethylene forming an insulating layer. Examples of such polyolefin-based base resins include low-density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-propylene copolymer, chlorinated polyethylene, and the like. Crosslinkable polymer blended with a product crosslinker. In addition, ethylene-
When using a vinyl acetate copolymer, it is desirable to use a vinyl acetate content of 10% by weight or more and 50% by weight or less. When the content of vinyl acetate is less than 10% by weight, the releasability is extremely deteriorated, and when the content is more than 50% by weight, the heat resistance is deteriorated, so that it can withstand the molding process for electric power cables and the like. Absent.

As the conductivity-imparting agent, a carbon black-based conductive material such as furnace black, acetylene black or Ketjen black can be used for uniform dispersibility.
It is desirable in terms of conductivity and durability. The addition amount of these carbon blacks is desirably from 10 to 100 parts by weight based on 100 parts by weight of the base resin. If the amount is less than 10 parts by weight, sufficient conductivity cannot be obtained. If the amount is more than 100 parts by weight, the extrudability is remarkably reduced, and sufficient strength is obtained when used as a semiconductive layer of a power cable. I can't.

The semiconductive resin composition according to the present invention may contain, as a filler, an organic peroxide (such as dicumyl peroxide or perhexine), an antioxidant, or a processing aid. desirable. It is desirable that such a filler be added in an amount of 5 to 30 parts by weight based on 100 parts by weight of the base resin. 5
If the amount is less than parts by weight, a sufficient effect of addition cannot be obtained, and
If the amount is more than 30 parts by weight, the processability is remarkably reduced.

The semiconductive resin composition of the present invention can be obtained by sufficiently kneading the above-mentioned raw materials with a kneading means such as a roll mill or a kneader. The temperature in the kneading step is desirably from 120 ° C to 150 ° C. 1
If the temperature is lower than 20 ° C., it is difficult to sufficiently knead the material.
If the temperature is 0 ° C. or higher, there is a risk of deterioration or thermal decomposition.

[0012]

EXAMPLES In the present Examples and Comparative Examples, the base resin was ethylene-vinyl acetate copolymer X700 manufactured by Mitsubishi Chemical Corporation.
(Vinyl acetate content: 30% by weight), # 3100 manufactured by Mitsubishi Chemical Corporation as carbon black as a conductivity-imparting agent, and Antage RD manufactured by Kawaguchi Chemical Industry Co., Ltd. as a filler.

[0013] In the examples, as a releasability-imparting agent, the viscosity is 0.5, 1, 10, 500 and 700 mPa / sec.
(Hereinafter referred to as “MPSi”) (hereinafter referred to as “MPSi”), and dimethyl silicone oil (TSF4 manufactured by Toray Dow Corning) used as a release agent in Comparative Examples
51-50, viscosity: 50 mPs / sec) (hereinafter "DM
Si ") was prepared.

These are mixed so as to have the compositions shown in Tables 1 and 2, and kneaded by a roll mill set at 140 ° C. until uniform, and the resin compositions A to I (Examples 1 to 9)
And resin compositions M to R (Comparative Examples 1 to 6).

For these resin compositions, the peel strength was J
It was measured according to IS K6766. In addition, it is considered that peeling is easy when the peeling strength is 0.3 kg / 10 mm or more and 0.8 kg / 10 mm or less.

Further, these resin compositions A to I and M to R
Was used to fabricate an insulated core of a crosslinked polyethylene insulated power cable. That is, as shown in the structural diagram of FIG. 1, these resin compositions are applied to the inner and outer semiconductive layers, and the inner semiconductive layer, the insulator (crosslinked polyethylene) and the outer conductive layer are coextruded at 180 ° C. by three layers. This was heated to 200 ° C. in a nitrogen atmosphere and chemically crosslinked to produce 18 types of dry-crosslinked 6 kV-CV (60 mm ² ) insulated cores (conductor thickness: 9.3 mm, internal Semiconductive layer thickness: 1m
m, insulating layer thickness: 3 mm, external semiconductive layer thickness: 1 mm).
The appearance of the insulated wire core obtained at this time was observed. The results are shown in Tables 1 and 2.

Further, the tree resistance of these resin compositions was evaluated. That is, these resin compositions were formed into a sheet having a thickness of 5 mm, and a resin layer of a conductive paint was provided on the bottom surface to form a ground electrode. On the other hand, a water tank was provided on the upper surface of the sheet to form a water electrode. After applying a voltage of 10 kV and 1 kHz to the water electrode for 30 days, the sample was boiled with boiling water, and the developed water tree was observed with a microscope. At this time, the relative number when the number of water trees generated in a comparative sample made of cross-linked polyethylene (XLPE) treated in the same manner was set to 100 was examined.
When the relative number is 20 or less, it is regarded as “good” and 20
It was evaluated as "poor" when it was super. These results are also shown in Tables 1 and 2.

[0018]

[Table 1]

[0019]

[Table 2]

Further, the semiconductive resin composition A according to the present invention
When the work of peeling the external semiconductive layer is performed on the insulated wire core of the power cable having the semiconductive layer formed by using I to I, it can be easily peeled off, and the surface of the insulating layer after the peeling has been performed. No carbon black remained. On the other hand, in the insulated wire core using the resin compositions M, P, and R, peeling was difficult, and carbon black remained. According to these results and Tables 1 and 2, it is found that when the semiconductive resin composition according to the present invention is used, an excellent insulated core of a power cable having a semiconductive layer which is easily peeled can be obtained.

[0021]

When the semiconductive resin composition according to the present invention is applied to the semiconductive layer of a crosslinked polyethylene insulated power cable, it has sufficient heat resistance for processing, excellent tree resistance, and appearance. A power cable having a semiconductive layer having excellent peelability can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of an insulated wire core of an insulated power cable having a semiconductive layer.

[Explanation of symbols]

 Reference Signs List 1 conductor 2 inner semiconductive layer 3 insulating layer (crosslinked polyethylene) 4 outer semiconductive layer

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C08L 23/00-23/36 C08L 83/04-83/08

Claims (4)

(57) [Claims] 1. A semiconductive resin composition comprising methylphenyl silicone oil as a component. 2. 100 parts by weight of a polyolefin-based resin, 10 parts by weight or more and 100 parts by weight or less of a conductivity-imparting agent, 5 parts by weight or more and 30 parts by weight or less of a filler, and 1 part by weight or more of methylphenyl silicone oil. The semiconductive resin composition according to claim 1, wherein the composition is mixed in an amount of 10 parts by weight or less. 3. The semiconductive resin composition according to claim 1, wherein the viscosity of the methylphenyl silicone oil is 1 mPa / sec or more and 500 mPa / sec or less. 4. A crosslinked polyethylene insulated power cable having a semiconductive layer, wherein the semiconductive layer contains methylphenyl silicone oil.